In typography, a font is traditionally defined as a quantity of sorts composing a complete character set of a single size and style of a particular typeface. For example, the set of all characters for 9-point Bulmer italic is a font, and the 10-point size would be a separate font, as would the 9-point upright.
After the introduction of computer fonts based on fully scalable outlines, a broader definition evolved. Font is no longer size-specific, but still refers to a single style. Bulmer regular, Bulmer italic, Bulmer bold and Bulmer bold italic are four fonts, but one typeface. However, the term font is also often used as a synonym for typeface.